Solar cell, concentrator photovoltaic unit, concentrator photovoltaic module, and method for producing concentrator photovoltaic module

ABSTRACT

Provided is a solar cell for which accurate mutual alignment between a condenser lens and a power generating element corresponding thereto can be performed. 
     In a solar cell  23 , a plurality of grid electrodes  31  each formed in a linear shape are arrayed on a light receiving surface  23   a  along the width direction of the light receiving surface  23   a . The plurality of grid electrodes  31  include a first center grid electrode  31   a  forming a cross portion  34  exhibiting a center-specific geometry caused by electrodes crossing each other at the center of the light receiving surface  23   a.

TECHNICAL FIELD

The present invention relates to a solar cell to be used in concentratorphotovoltaic (CPV), a concentrator photovoltaic unit and a concentratorphotovoltaic module each using the solar cell, and a method forproducing the concentrator photovoltaic module.

BACKGROUND ART

Concentrator photovoltaic is based on a structure in which a solar cellformed by a small compound semiconductor element or the like having highpower generation efficiency is irradiated with sunlight concentrated bya Fresnel lens (see PATENT LITERATURE 1, for example). A large number ofsuch basic units are arranged in a matrix shape in one housing, therebyto form a concentrator photovoltaic module. A plurality of the modulesare arranged, thereby to form a concentrator photovoltaic panel. Bycausing this concentrator photovoltaic panel to perform trackingoperation so as to always face the sun, it is possible to obtain adesired generated power.

CITATION LIST Patent Literature

PATENT LITERATURE 1: U.S. Pat. No. 4,069,812

SUMMARY OF INVENTION Technical Problem

During production of the concentrator photovoltaic module as describedabove, it is necessary to perform alignment precisely such that, on theoptical axis of each condenser lens such as a Fresnel lens, the centerof its corresponding solar cell is positioned. Mutual alignment betweensolar cells and condenser lenses can be attained by ensuring theirmounting accuracy relative to the common housing, for example. However,only doing this may allow minute individual differences, which mayresult in misalignment between the optical axis of each condenser lensand the center of its corresponding solar cell. If misalignment occurs,power generation efficiency is reduced.

In the basic unit above, as shown in FIG. 3, there are cases wherebetween the solar cell and the condenser lens such as a Fresnel lens, aball lens as a secondary condenser lens is disposed immediately beforethe light receiving surface of the solar cell, so as to cover the lightreceiving surface.

FIG. 13A shows the light receiving surface of the solar cell. A lightreceiving surface 200 a of a solar cell 200 to be used in theconcentrator photovoltaic module has a rectangular shape as shown, andone side of the rectangular shape is generally about several millimeterslong.

In a case where the secondary condenser lens such as a ball lens is notprovided, the center portion of the light receiving surface 200 a can berecognized based on a contour 201 of the light receiving surface 200 a.

However, when a ball lens is disposed immediately before the lightreceiving surface 200 a of the solar cell, there are cases where thecontour 201 cannot be recognized because the light receiving surface 200a is covered by the ball lens. Even when the light receiving surface 200a can be seen through the ball lens, only a part of grid electrodes 203formed on the light receiving surface 200 a can be confirmed, and thecenter of the light receiving surface 200 a is difficult to berecognized.

FIG. 13B shows one example of a captured image of a ball lens as asecondary condenser lens, when the ball lens is disposed immediatelybefore the light receiving surface 200 a of the solar cell, the imagecaptured by a camera or the like from the irradiation direction in whichthe ball lens is irradiated with sunlight.

In the captured image shown in FIG. 13B, there appear an image portion302 of the ball lens and image portions 303 of only a part of the gridelectrodes 203 confirmed through the ball lens in the image portion 302.The part corresponding to the contour of the light receiving surface 200a does not appear.

Thus, when the ball lens is disposed immediately before the lightreceiving surface 200 a, it becomes difficult to recognize the center ofthe light receiving surface 200 a. Thus, it becomes difficult toaccurately align the optical axis of the ball lens with the center ofthe solar cell 200, whereby misalignment is caused. Due to thismisalignment, further misalignment is caused also between the opticalaxis of the ball lens and the optical axis of the condenser lens,whereby power generation efficiency is reduced.

The present invention has been made in view of the above circumstances.An object of the present invention is to provide a technology thatallows accurate mutual alignment between the condenser lens and itscorresponding solar cell.

Solution to Problem

A solar cell being one embodiment is a solar cell in which a pluralityof grid electrodes each formed in a linear shape are arrayed on a lightreceiving surface of the solar cell, wherein the plurality of gridelectrodes include a cross grid electrode forming a cross portionexhibiting a center-specific geometry caused by electrodes crossing eachother at a center of the light receiving surface.

A concentrator photovoltaic unit being one embodiment is a concentratorphotovoltaic unit including: a solar cell in which a plurality of gridelectrodes each formed in a linear shape are arrayed on a lightreceiving surface of the solar cell; and a condenser lens configured toconcentrate sunlight on the solar cell, wherein the plurality of gridelectrodes include a cross grid electrode forming a cross portionexhibiting a center-specific geometry caused by electrodes crossing eachother at a center of the light receiving surface.

A concentrator photovoltaic module being one embodiment includes: aplurality of solar cells provided in a form of an array; and aconcentrating member in which a plurality of condenser lenses eachconcentrating sunlight incident on an incident surface thereof areformed at positions corresponding to the solar cells on optical axesthereof, wherein on a light receiving surface of each solar cell, aplurality of grid electrodes each formed in a linear shape are arrayed,and the plurality of grid electrodes include a cross grid electrodeforming a cross portion exhibiting a center-specific geometry caused byelectrodes crossing each other at a center of the light receivingsurface.

A method for producing a concentrator photovoltaic module being oneembodiment is a method for producing a concentrator photovoltaic moduleincluding: a plurality of solar cells provided in a form of an array;and a concentrating member in which a plurality of condenser lenses eachconcentrating sunlight incident on an incident surface thereof areformed at positions corresponding to the solar cells on optical axesthereof, wherein on a light receiving surface of each solar cell, aplurality of grid electrodes each formed in a linear shape are arrayed,and the plurality of grid electrodes include a cross grid electrodeforming a cross portion exhibiting a center-specific geometry caused byelectrodes crossing each other at a center of the light receivingsurface, the method including: a position information obtaining step ofobtaining position information indicating positional relation between acondenser lens and a cross portion corresponding thereto at a time whenthe condenser lens and a solar cell corresponding thereto are seen fromthe incident surface side of the condenser lens; and an adjustment stepof performing positional adjustment between the concentrating member andeach solar cell based on the position information.

Advantageous Effects of Invention

According to the present invention, it is possible to perform accuratemutual alignment between the condenser lens and its corresponding solarcell.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing one example of a concentratorphotovoltaic apparatus.

FIG. 2 is a perspective view (partially cut out) showing an enlargedview of one example of a concentrator photovoltaic module.

FIG. 3 is a schematic diagram showing a concentrator photovoltaic unit.

FIG. 4 shows a light receiving surface of a solar cell.

FIG. 5A shows a mounting device for mounting a ball lens onto the solarcell side, and a mounting method therefor, and shows the mounting deviceis disposed above the light receiving surface of the solar cell on aflexible substrate on which the ball lens is to be mounted.

FIG. 5B shows the ball lens is inserted in a holding hole of a holder.

FIG. 5C shows the holder is removed.

FIG. 6 shows one example of a captured image obtained by a camera partin a state of FIG. 5B.

FIG. 7 is a perspective view showing one example of the manner ofperforming positioning when a lens panel is to be mounted on a housing.

FIG. 8A is a front view of a Fresnel lens.

FIG. 8B shows positional relation between a Fresnel lens and a powergenerating element part of one unit.

FIG. 8C is a front view of the power generating element part.

FIG. 9 is a graph showing one example of details of a Fresnel pattern.

FIG. 10A shows a power generating element part viewed from the centerregion of a Fresnel lens. FIG. 10A also shows a position of the Fresnellens where a part of the ball lens of the power generating element partis seen at a not-aligned position.

FIG. 10B shows a state where a linear electrode portion and a crossportion appear in the center region.

FIG. 10C shows a state where the cross portion has come to substantiallythe center of the center region.

FIG. 11 shows a light receiving surface of a solar cell according to amodification and shows another aspect of a linear electrode portion.

FIG. 12A shows a solar cell according to another embodiment, and shows alight receiving surface of the solar cell.

FIG. 12B shows one example of a captured image of the light receivingsurface shown in FIG. 12A obtained by a camera part through a ball lens.

FIG. 13A shows a light receiving surface of a solar cell, and FIG. 13Bshows one example of a captured image of a ball lens as a secondarycondenser lens, when the ball lens is disposed immediately before thelight receiving surface of the solar cell, the image captured by acamera or the like from the irradiation direction in which the ball lensis irradiated with sunlight.

DESCRIPTION OF EMBODIMENTS

[Description of Embodiments of the Present Invention]

First, contents of embodiments of the present invention will be listedfor description.

(1) A solar cell being one embodiment is a solar cell in which aplurality of grid electrodes each formed in a linear shape are arrayedon a light receiving surface of the solar cell, wherein the plurality ofgrid electrodes include a cross grid electrode forming a cross portionexhibiting a center-specific geometry caused by electrodes crossing eachother at a center of the light receiving surface.

According to the solar cell having the above configuration, theplurality of grid electrodes include the cross grid electrode formingthe cross portion exhibiting the center-specific geometry caused byelectrodes crossing each other at the center of the light receivingsurface. Thus, when a condenser lens concentrating sunlight to the lightreceiving surface is to be disposed, the position of the cross portioncan be recognized through the condenser lens. Thus, it is possible toaccurately adjust the position of the optical axis of the condenser lensto the center of the light receiving surface, based on the positionalrelation between the condenser lens and the cross portion. As a result,it is possible to perform accurate mutual alignment between thecondenser lens and its corresponding solar cell.

(2) In the above solar cell, preferably, the cross grid electrode is acenter grid electrode extending in parallel to other grid electrodes andpassing the center of the light receiving surface, and the center gridelectrode is provided with a linear electrode portion crossing thecenter grid electrode at the center of the light receiving surface.

In this case, when the solar cell having the center grid electrodeextending in parallel to other grid electrodes and passing the center ofthe light receiving surface is used, it is possible to form the crossportion only by providing the linear electrode portion. Accordingly, itis possible to provide the cross portion without greatly increasing thearea of the grid electrodes.

(3) Further, preferably, the linear electrode portion has both endsthereof respectively connected to grid electrodes disposed on both sidesof the center grid electrode. In this case, by the linear electrodeportion being connected to the center grid electrode and to one pair ofgrid electrodes disposed on both sides of the center grid electrode, itis possible to suppress easy detachment of the linear electrode portionfrom the light receiving surface.

(4) The cross grid electrode may be a pair of center grid electrodesarrayed in a center portion in a width direction of the light receivingsurface, each center grid electrode passing the center of the lightreceiving surface, and the pair of center grid electrodes may include:oblique electrode portions forming the cross portion by extending indirections that cross other grid electrodes and by crossing each other;and parallel electrode portions each extending in parallel to the othergrid electrodes, from both ends of a corresponding one of the obliqueelectrode portions toward edge sides of the light receiving surface.

In this case, even when the solar cell does not include the gridelectrode extending in parallel to other grid electrodes and passing thecenter of the light receiving surface, by providing the pair of centergrid electrodes including the oblique electrode portions, it is possibleto form the cross portion. Accordingly, it is possible to provide thecross portion without greatly increasing the area of the gridelectrodes.

(5) A concentrator photovoltaic unit being one embodiment is aconcentrator photovoltaic unit including: a solar cell in which aplurality of grid electrodes each formed in a linear shape are arrayedon a light receiving surface of the solar cell; and a condenser lensconfigured to concentrate sunlight on the solar cell, wherein theplurality of grid electrodes include a cross grid electrode forming across portion exhibiting a center-specific geometry caused by electrodescrossing each other at a center of the light receiving surface.

According to the concentrator photovoltaic unit having the aboveconfiguration, the plurality of grid electrodes include the cross gridelectrode forming the cross portion exhibiting the center-specificgeometry caused by electrodes crossing each other at the center of thelight receiving surface. Thus, when a condenser lens is to be disposed,the position of the cross portion can be recognized through thecondenser lens. Thus, it is possible to accurately adjust the positionof the optical axis of the condenser lens to the center of the lightreceiving surface, based on the positional relation between thecondenser lens and the cross portion. As a result, it is possible toperform accurate mutual alignment between the condenser lens and itscorresponding solar cell.

(6) The above concentrator photovoltaic unit may further include asecondary condenser lens disposed between the condenser lens and thesolar cell and configured to guide sunlight concentrated by thecondenser lens to the solar cell. Also in this case, based on thepositional relation between each condenser lens and its correspondingcross portion, it is possible to accurately adjust the position of theoptical axis of each condenser lens to the center of the light receivingsurface. As a result, even when the secondary condenser lens isprovided, it is possible to perform accurate mutual alignment betweeneach condenser lens and its corresponding solar cell.

(7) Further, even when the secondary condenser lens is a ball lens andis fixed to the solar cell side so as to cover the light receivingsurface of the solar cell, it is possible to recognize the position ofthe cross portion through each condenser lens. Thus, it is possible toperform accurate mutual alignment between each condenser lens and itscorresponding solar cell.

(8) A concentrator photovoltaic module being one embodiment is aconcentrator photovoltaic module including: a plurality of solar cellsprovided in a form of an array; and a concentrating member in which aplurality of condenser lenses each concentrating sunlight incident on anincident surface thereof are formed at positions corresponding to thesolar cells on optical axes thereof, wherein on a light receivingsurface of each solar cell, a plurality of grid electrodes each formedin a linear shape are arrayed, and the plurality of grid electrodesinclude a cross grid electrode forming a cross portion exhibiting acenter-specific geometry caused by electrodes crossing each other at acenter of the light receiving surface.

According to the concentrator photovoltaic module having the aboveconfiguration, the plurality of grid electrodes include the cross gridelectrode forming the cross portion exhibiting the center-specificgeometry caused by electrodes crossing each other at the center of thelight receiving surface. Thus, when a condenser lens is to be disposed,the position of the cross portion can be recognized through thecondenser lens. Thus, it is possible to accurately adjust the positionof the optical axis of the condenser lens to the center of the lightreceiving surface, based on the positional relation between thecondenser lens and the cross portion. As a result, it is possible toperform accurate mutual alignment between the concentrating member andeach solar cell.

(9) A method for producing a concentrator photovoltaic module being oneembodiment is a method for producing a concentrator photovoltaic moduleincluding: a plurality of solar cells provided in a form of an array;and a concentrating member in which a plurality of condenser lenses eachconcentrating sunlight incident on an incident surface thereof areformed at positions corresponding to the solar cells on optical axesthereof, wherein on a light receiving surface of each solar cell, aplurality of grid electrodes each formed in a linear shape are arrayed,and the plurality of grid electrodes include a cross grid electrodeforming a cross portion exhibiting a center-specific geometry caused byelectrodes crossing each other at a center of the light receivingsurface, the method including: a position information obtaining step ofobtaining position information indicating positional relation between acondenser lens and a cross portion corresponding thereto at a time whenthe condenser lens and a solar cell corresponding thereto are seen fromthe incident surface side of the condenser lens; and an adjustment stepof performing positional adjustment between the concentrating member andeach solar cell based on the position information.

According to the method for producing the concentrator photovoltaicmodule having the above configuration, it is possible to easilyrecognize the center of the light receiving surface by means of thecross portion formed on the light receiving surface of the solar cell,and it is possible to perform accurate mutual alignment between theconcentrating member and each solar cell.

(10) In the method for producing the concentrator photovoltaic module,in a case where the concentrator photovoltaic module further includes asecondary condenser lens disposed between each condenser lens and asolar cell corresponding thereto, each secondary condenser lens guidingsunlight concentrated by the condenser lens to the solar cell, it ispreferable that the method further includes: prior to the positioninformation obtaining step, a secondary condenser lens positioninformation obtaining step of obtaining secondary condenser lensposition information indicating positional relation between a secondarycondenser lens and the cross portion at a time when the secondarycondenser lens and the solar cell are seen from an incident surface sideof the secondary condenser lens; and a secondary condenser lensadjustment step of performing positional adjustment between thesecondary condenser lens and the solar cell based on the secondarycondenser lens position information.

In this case, it is possible to easily recognize the center of the lightreceiving surface by means of the cross portion formed on the lightreceiving surface of the solar cell, and thus, it is possible to performaccurate mutual alignment between the secondary condenser lens and thesolar cell. In addition, the mutual alignment between the concentratingmember and the solar cells to be performed thereafter can be moreaccurately performed by means of the cross portion.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Hereinafter, preferable embodiments will be described with reference tothe drawings.

1. CONFIGURATION OF CONCENTRATOR PHOTOVOLTAIC MODULE

FIG. 1 is a perspective view showing one example of a concentratorphotovoltaic apparatus. In FIG. 1, a concentrator photovoltaic apparatus100 includes a concentrator photovoltaic panel 1, a post 2 whichsupports the concentrator photovoltaic panel 1 on the rear surface sidethereof, and a base 3 on which the post 2 is mounted.

The concentrator photovoltaic panel 1 is formed by assembling a largenumber of concentrator photovoltaic modules 1M vertically andhorizontally. In this example, 62 (7 in length×9 in breadth−1)concentrator photovoltaic modules 1M are assembled vertically andhorizontally, except the center portion. When one concentratorphotovoltaic module 1M has a rated output of, for example, about 100 W,the entirety of the concentrator photovoltaic panel 1 has a rated outputof about 6 kW.

On the rear surface side of the concentrator photovoltaic panel 1, adriving device (not shown) is provided. By operating this drivingdevice, it is possible to cause the concentrator photovoltaic panel 1 totrack the sun while always facing the direction of the sun.

FIG. 2 is a perspective view (partially cut out) showing an enlargedview of one example of the concentrator photovoltaic module(hereinafter, also simply referred to as “module”) 1M. Three directionsorthogonal with one another are defined as X, Y, and Z, as shown in FIG.2.

In FIG. 2, the module 1M includes: a housing 11 formed in a vessel shapeand having a bottom surface 11 a on an X-Y plane; a plurality offlexible printed circuits 12 provided on the bottom surface 11 a; and alens panel 13 (concentrating member) having a rectangular shape (shownin a state of being partially cut out), mounted on an end surface 15 aof a wall part 15 standing from the periphery of the bottom surface 11a, and closing an opening 11 c of the housing 11. The housing 11 is madeof metal, for example, and an aluminium alloy which is excellent inthermal conductivity in particular is suitable therefor.

The lens panel 13 is a Fresnel lens array and is formed by arranging, ina matrix shape, a plurality of (for example, 16 in length×12 in breadth,192 in total) Fresnel lenses 13 f as lens elements which concentratesunlight. Each Fresnel lens 13 f forms a square effective concentrationregion. The lens panel 13 can be obtained by, for example, forming asilicone resin film on the back surface (inside) of a glass plate usedas a base material. Each Fresnel lens 13 f is formed on this siliconeresin film. On the external surface of the housing 11, a connector 14for taking out an output from the module 1M is provided.

Each flexible printed circuit 12 includes: a flexible substrate 16, of aribbon shape, on which a necessary conduction pattern is provided; and aplurality of power generating element parts 21 provided on this flexiblesubstrate 16. In the example shown in FIG. 2, each flexible printedcircuit 12 has eight power generating element parts 21 mounted thereon.The flexible printed circuits 12 are arranged in a plurality of rowsalong the longitudinal direction of the housing 11, and 24 flexibleprinted circuits 12 are arranged in total. Thus, the total number of thepower generating element parts 21 is 192 (24×8). That is, the number ofthe power generating element parts 21 is the same as the number of theFresnel lenses 13 f of the lens panel 13. Further, the power generatingelement parts 21 are provided on the optical axes of their correspondingFresnel lenses 13 f, respectively.

A Fresnel lens 13 f and a power generating element part 21 provided soas to correspond to each other form a concentrator photovoltaic unit asan optical system basic unit for constructing the module 1M describedabove.

FIG. 3 is a schematic diagram showing the concentrator photovoltaicunit.

In FIG. 3, a photovoltaic unit (hereinafter, also simply referred to as“unit”) 20 includes the Fresnel lens 13 f and the power generatingelement part 21 as described above.

The Fresnel lens 13 f concentrates sunlight incident from an incidentsurface 13 f 1, onto the power generating element part 21 provided so asto correspond thereto.

The power generating element part 21 includes a solar cell 23 being apower generating element, and a ball lens 24.

The solar cell 23 is packaged on the flexible substrate 16 by a resinframe 22 surrounding the solar cell 23, with a light receiving surface23 a thereof exposed.

The Fresnel lens 13 f is disposed such that the optical axis S of theFresnel lens 13 f is parallel to the Z direction and such that theoptical axis S passes the center of the light receiving surface 23 a.

The ball lens 24 is disposed at a position at which the ball lens 24 canappropriately guide sunlight toward the light receiving surface 23 a, bythe center of the ball lens 24 being disposed on the optical axis S.

FIG. 4 shows the light receiving surface 23 a of the solar cell 23.

The solar cell 23 includes: a semiconductor substrate 30 whose one faceserves as the light receiving surface 23 a having a rectangular shape; aplurality of linear grid electrodes 31 arrayed on the light receivingsurface 23 a; and a pair of bus electrodes 32 provided at edge portionsof the semiconductor substrate 30 and respectively connected to bothends of each of these grid electrodes 31.

In FIG. 4, the portions with hatching indicate the places where the gridelectrodes 31 and the bus electrodes 32 are provided, and the portionswithout hatching indicate the places where the semiconductor substrate30 is exposed.

Each grid electrode 31 is an electrode formed by a conductor such assilver in a thin line shape, and has a function of collecting electricenergy obtained by conversion of sunlight received by the semiconductorsubstrate 30.

Each bus electrodes 32 is an electrode formed by a conductor such assilver, as in the case of the grid electrode 31, and has a function ofoutputting electric energy collected by the grid electrodes 31, tooutside. The bus electrodes 32 are respectively formed along both sideedges, of the semiconductor substrate 30, that are parallel to thedirection that crosses the longitudinal direction of the grid electrodes31 on the semiconductor substrate 30.

The grid electrodes 31 extend in parallel to edge portions of the lightreceiving surface 23 a where the bus electrodes 32 are not provided, andare arrayed, on the light receiving surface 23 a, along the longitudinaldirection of the bus electrodes 32.

These grid electrodes 31 include a first center grid electrode 31 apassing the center of the light receiving surface 23 a.

The first center grid electrode 31 a extends in parallel to the othergrid electrodes 31. This first center grid electrode 31 a is providedwith a linear electrode portion 33 which crosses the first center gridelectrode 31 a at the center of the light receiving surface 23 a.

The linear electrode portion 33 is formed in parallel to the directionin which the bus electrodes 32 extend. Both ends of the linear electrodeportion 33 are respectively connected to the grid electrodes 31 that arerespectively disposed on both sides of the first center grid electrode31 a.

Accordingly, for example, when compared with a case where both ends ofthe linear electrode portion 33 are not connected to the grid electrodes31 that are respectively disposed on both sides of the first center gridelectrode 31 a, i.e., the linear electrode portion 33 is in an openstate, it is possible to suppress easy detachment of the linearelectrode portion 33 from the light receiving surface 23 a.

The first center grid electrode 31 a forms a cross portion 34 bycrossing the linear electrode portion 33 at the center of the lightreceiving surface 23 a.

In the light receiving surface 23 a of the present embodiment, there isno portion where electrodes cross each other, except the cross portion34. The cross portion 34 exhibits a center-specific geometry, by theelectrodes crossing each other at the center of the light receivingsurface 23 a.

In this manner, the first center grid electrode 31 a constitutes a crossgrid electrode in which the cross portion 34 is formed that exhibits acenter-specific geometry caused by electrodes crossing each other at thecenter of the light receiving surface 23 a. The cross portion 34indicates the center of the light receiving surface 23 a.

With reference back to FIG. 3, the ball lens 24 is a spherical lensformed by use of borosilicate-based glass or quartz-based glass, forexample. The ball lens 24 is fixed to the resin frame 22 by being bondedwith a silicone resin, an acrylic resin, or the like. Accordingly, theball lens 24 is fixed to the solar cell 23, with a slight gaptherebetween.

In general, the ball lens 24 that has a diameter greater than thedimensions of the light receiving surface 23 a is used from theviewpoint of efficiency. Thus, as shown in FIG. 3, the ball lens 24 isfixed to the resin frame 22 on the flexible substrate 16 being the solarcell 23 side, so as to cover the entirety of the light receiving surface23 a of the solar cell 23.

The slight gap between the ball lens 24 and the solar cell 23 may befilled with the silicone resin, the acrylic resin, or the like that isused for the fixing by bonding as described above.

The ball lens 24 is disposed between the Fresnel lens 13 f and the solarcell 23, so as to receive sunlight concentrated by the Fresnel lens 13 fto guide the sunlight to the solar cell 23. That is, the Fresnel lens 13f forms a primary condenser lens, and the ball lens 24 forms a secondarycondenser lens.

In this configuration, sunlight is concentrated by the Fresnel lens 13 fbeing the primary condenser lens, then further concentrated by the balllens 24 being the secondary condenser lens, to be emitted onto the solarcell 23. Therefore, a large amount of light energy can be concentratedon the solar cell 23, and thus, power can be generated at highefficiency.

The module 1M includes a plurality of units 20 which each can generatepower at high efficiency as described above, and outputs power generatedby each unit 20 from the connector 14 (FIG. 2).

2. METHOD FOR PRODUCING CONCENTRATOR PHOTOVOLTAIC MODULE

Next, of the method for producing the module 1M, a method for mountingthe ball lens 24 on the flexible substrate 16 side, and alignment at thetime of mounting the lens panel 13 of the module 1M onto the housing 11will be described in particular.

[2.1 Method for Mounting the Ball Lens 24]

As described above, when the ball lens 24 is greatly misaligned from thelight receiving surface 23 a of the solar cell 23, power generationefficiency is reduced.

Thus, when each ball lens 24 is to be fixed to the housing 11, the balllens 24 needs to be fixed after positional adjustment has been performedsuch that the optical axis of the ball lens 24 is accurately alignedwith the light receiving surface 23 a of the solar cell 23 correspondingto the ball lens 24.

FIG. 5A shows a mounting device for mounting the ball lens 24 onto thesolar cell 23 side, and a mounting method therefor.

In FIG. 5A, a ball lens mounting device 40 for mounting the ball lens 24includes: a positional adjustment section 41 capable of performingpositional adjustment by moving the ball lens 24 while holding the balllens 24 above the flexible substrate 16; a controller 42 configured tocontrol the positional adjustment section 41; and a camera part 43configured to capture an image of the ball lens 24 and the solar cell 23side through the ball lens 24.

The positional adjustment section 41 includes a holder 44 configured tohold the ball lens 24 above the flexible substrate 16, and a drive unit45 configured to drive the holder 44 based on an instruction from thecontroller 42. The holder 44 is configured to be able to move in X-Ydirections while holding the ball lens 24 in a holding hole 44 a. Theholder 44 is driven by the drive unit 45, and performs positionaladjustment between the ball lens 24 and the light receiving surface 23 aof the solar cell 23 by moving the held ball lens 24 in X-Y directions.

The camera part 43 is configured to capture an image of a predeterminedimaging range to generate captured image data, and configured tocontinuously provide the captured image data to the controller 42 at apredetermined time interval.

The camera part 43 is disposed such that the imaging direction at thetime when the camera part 43 captures an image of a predeterminedimaging range is parallel to the Z direction and such that the center ofthe imaging range matches the position on the X-Y coordinate system ofthe center of the light receiving surface 23 a.

The camera part 43 disposed in this manner is configured to capture animage of the ball lens 24 and the light receiving surface 23 a viewedthrough the ball lens 24, along the optical axis S of the Fresnel lens13 f to be disposed in a later step.

Upon receiving the captured image data from the camera part 43, thecontroller 42 obtains position information (ball lens positioninformation) indicating the positional relation between the ball lens 24and the light receiving surface 23 a of the solar cell 23, based on thecaptured image. Then, the controller 42 generates an instruction formoving the ball lens 24 to an appropriate position based on thisposition information, and provides the instruction to the drive unit 45.

By use of the ball lens mounting device 40, the ball lens 24 is mountedon the solar cell 23 side as follows.

First, as shown in FIG. 5A, the ball lens mounting device 40 is disposedabove the light receiving surface 23 a of the solar cell 23 on theflexible substrate 16 on which the ball lens 24 is to be mounted.

Next, as shown in FIG. 5B, the ball lens 24 is inserted in the holdinghole 44 a of the holder 44. The holding hole 44 a is configured to holdthe ball lens 24 so as to allow the ball lens 24 to be moved in X-Ydirections, and configured to allow the ball lens 24 to be easilyremoved therefrom.

Thus, by being inserted in the holding hole 44 a, the ball lens 24 ismovably held therein.

As shown in FIG. 5B, the ball lens 24 is disposed on the resin frame 22while being held in the holding hole 44 a.

In the state of FIG. 5B, the camera part 43 captures an image of theball lens 24 and the light receiving surface 23 a recognized through theball lens 24, in parallel to the optical axis S, from an incidentsurface 24 a side of the ball lens 24.

FIG. 6 shows one example of the captured image obtained by the camerapart 43 in the state of FIG. 5B.

Since the diameter of the ball lens 24 is set to a greater value thanthe values of the dimensions of the light receiving surface 23 a of thesolar cell 23, the entirety of the light receiving surface 23 a iscovered by the ball lens 24. Thus, the contour of the light receivingsurface 23 a cannot be recognized on a captured image 50.

On the other hand, the grid electrodes 31 formed on the light receivingsurface 23 a can be recognized through the ball lens 24. As shown inFIG. 6, in the captured image 50, an image portion 51 of the ball lens24 appears, and many image portions 52 of the grid electrodes 31 thatcan be recognized through the ball lens 24 appear in the image portion51 of the ball lens 24. In FIG. 6, the portions with hatching indicatethe image portions 52 of the grid electrodes 31.

Since the ball lens 24 has a spherical shape, the incident surface 24 aalso has a round surface being a part of the spherical shape. Thus, inthe images of the grid electrodes 31 recognized through the ball lens 24when the ball lens 24 is seen in parallel to the optical axis S,distortion occurs due to the curvature of the incident surface 24 a, inaccordance with the increase in the distance from the center portion ofthe ball lens 24. Thus, as shown in FIG. 6, the image portions 52 of thegrid electrodes 31 appearing in the image portion 51 of the ball lens 24are distorted to an extent that the linearity of the grid electrodes 31cannot be recognized, in accordance with the increase in the distancefrom the center portion of the ball lens 24.

However, the image portions 52 of the grid electrodes 31 in the centerportion of the image portion 51 of the ball lens 24 appear relativelyclear to an extent that the linearity of the grid electrodes 31 can berecognized. Thus, it is seen that the grid electrodes 31 can berelatively clearly recognized in the center portion the ball lens 24.

Here, in the center portion of the image portion 51 of the ball lens 24shown in FIG. 6, there appear an image portion 52 a of the first centergrid electrode 31 a passing the center of the light receiving surface 23a, and an image portion 53 of the linear electrode portion 33 formingthe cross portion 34 with the first center grid electrode 31 a.

In this manner, in the center portion of the ball lens 24, the shapes ofthe grid electrodes 31 can be recognized.

Thus, by adjusting the position of the ball lens 24 such that the crossportion 34 formed by the first center grid electrode 31 a and the linearelectrode portion 33 substantially matches the center of the contour ofthe ball lens 24, the ball lens 24 can be accurately disposed on theoptical axis S.

That is, when the position of the ball lens 24 is adjusted such that, inthe captured image 50 obtained by the camera part 43, an image portion54 of the cross portion 34 is positioned at the center of the contour ofthe image portion 51 of the ball lens 24, the center being specifiedbased on the contour of the image portion 51, the center of the balllens 24 can be accurately disposed so as to be on the optical axis S.

Thus, upon receiving the captured image data from the camera part 43,the controller 42 specifies the contour of the image portion 51 of theball lens 24 and the image portion 54 of the cross portion 34 based onthe captured image 50, and then obtains ball lens position informationindicating the positional relation between the ball lens 24 and thecross portion 34 of the solar cell 23 (secondary condenser lens positioninformation obtaining step).

Further, based on the ball lens position information, the controller 42obtains a movement amount necessary for bringing the cross portion 34 tothe center of the contour of the ball lens 24. The controller 42provides this movement amount as an instruction to the drive unit 45.

In accordance with the movement amount provided by the controller 42,the drive unit 45 moves the holder 44 to adjust the position of the balllens 24 (secondary condenser lens adjustment step).

In this manner, the controller 42 repeats obtainment of the ball lensposition information and positional adjustment of the ball lens 24 basedon the ball lens position information, thereby to dispose the ball lens24 at an appropriate position.

In the present embodiment, a case has been described in which thecontroller 42 provides the drive unit 45 with a movement amountnecessary for bringing the cross portion 34 to the center of the contourof the ball lens 24. However, for example, the controller 42 may providedisplay of the movement amount to an operator of the ball lens mountingdevice 40, and the operator having confirmed the display may operate thepositional adjustment section 41 based on the movement amount, to adjustthe position of the ball lens 24.

In the above, a case has been described in which the ball lens mountingdevice 40 is configured to perform adjustment by moving the ball lens 24relative to the light receiving surface 23 a. However, the ball lens 24may be fixed, and the ball lens mounting device 40 may performadjustment by moving the solar cell 23 side relative to the fixed balllens 24.

As shown in FIG. 5C, when the positional adjustment of the ball lens 24is completed, in order to fix the ball lens 24 at that position, a resin25 for fixing by bonding is attached to the boundary portion between theball lens 24 and the resin frame 22, and the ball lens 24 and the resinframe 22 are bonded and fixed together.

When bonding and fixing the ball lens 24 and the resin frame 22 togetherhave been completed, and the holder 44 is removed, mounting of the balllens 24 is completed.

The controller 42 may be configured by a computer including a CPU, astorage device, and the like, in which the functions as the controller42 are realized by a computer program. In the storage device, thecomputer program for realizing the functions as the controller 42 isalso stored.

This computer program is a computer program for causing a computer toexecute a process regarding production of a concentrator photovoltaicmodule including:

a plurality of solar cells provided in a form of an array; and

a concentrating member in which a plurality of condenser lenses eachconcentrating sunlight incident on an incident surface thereof areformed at positions corresponding to the solar cells on optical axesthereof, wherein

on a light receiving surface of each solar cell, a plurality of gridelectrodes each formed in a linear shape are arrayed, and

the plurality of grid electrodes include a cross grid electrode forminga cross portion exhibiting a center-specific geometry caused byelectrodes crossing each other at the center of the light receivingsurface,

the computer program for causing the computer to execute:

-   -   prior to a position information obtaining step of obtaining        position information indicating positional relation between a        condenser lens and a cross portion corresponding thereto at a        time when the condenser lens and a solar cell corresponding        thereto are seen from the incident surface side of the condenser        lens,    -   a secondary condenser lens position information obtaining step        of obtaining secondary condenser lens position information        indicating positional relation between a secondary condenser        lens (the ball lens 24) and the cross portion at a time when the        solar cell and the secondary condenser lens are seen from an        incident surface side of the secondary condenser lens; and    -   a secondary condenser lens adjustment step of performing        positional adjustment between the secondary condenser lens and        the solar cell based on the secondary condenser lens position        information.

[2.2 Alignment of the Lens Panel 13]

As described above, each power generating element part 21 (solar cell23) is provided on the optical axis S of its corresponding Fresnel lens13 f. If the power generating element part 21 is greatly misaligned fromthe optical axis of the Fresnel lens 13 f, power generation efficiencyis reduced.

Therefore, when the lens panel 13 is to be fixed to the housing 11, itis necessary to perform positional adjustment such that the optical axisof each Fresnel lens 13 f of the lens panel 13 is accurately alignedwith its corresponding power generating element part 21 provided in thehousing 11.

FIG. 7 is a perspective view showing one example of the manner ofperforming positioning when the lens panel 13 is to be mounted on thehousing 11. In FIG. 7, three directions orthogonal with one another aredefined as X, Y, and Z, as shown.

For example, four cameras 60 to 63 are prepared as image capturingdevices, and the cameras 60 to 63 respectively capture, through Fresnellenses 13 f at four corners of the lens panel 13, images of the powergenerating element parts 21 at their corresponding positions. Thepositions on the X-Y coordinate system of the cameras 60 to 63 match thepositions of their corresponding power generating element parts 21 atthe four corners. Therefore, each of the cameras 60 to 63 captures animage at a time when its corresponding Fresnel lens 13 f and powergenerating element part 21 are seen along the optical axis S of theFresnel lens 13 f from the incident surface 13 f 1 side of the Fresnellens 13 f.

Data of the captured images obtained by the cameras 60 to 63 areprovided to a control device 65.

The control device 65 is a device, such as a personal computer, thatperforms image information processing. Based on the captured image dataprovided from the cameras 60 to 63, the control device 65 obtainsposition information indicating the positional relations between theFresnel lenses 13 f and the power generating element parts 21.

Based on the obtained position information, the control device 65 causesa position adjuster 66 to operate so as to move the lens panel 13 to anappropriate position, whereby the control device 65 performs positionaladjustment between the lens panel 13 and the power generating elementparts 21. The position adjuster 66 can move the lens panel 13 in X-Ydirections and also can slightly rotate the lens panel 13 on an X-Yplane.

FIG. 8B shows positional relation between the Fresnel lens 13 f and thepower generating element part 21 of one unit. It should be noted thatthe dimensions of each part are not necessarily uniformly to scale. FIG.8A is a front view of the Fresnel lens 13 f, and FIG. 8C is a front viewof the power generating element part 21.

For example, the Fresnel lens 13 f is formed in a square shape havingone side of 50 mm, the light receiving surface 23 a of the solar cell 23of the power generating element part 21 is formed in a square shapehaving one side of 3.5 mm, and the ball lens 24 is disposed immediatelybefore the light receiving surface 23 a. As described above, the Fresnellens 13 f is composed of a base material 13 f 2 being a glass plate, anda silicone resin film 13 f 3 being the lens body.

Sunlight concentrated by the Fresnel lens 13 f is incident on the powergenerating element part 21.

As shown in FIG. 8A, the Fresnel lens 13 f (the silicone resin film 13 f3) has a concentric Fresnel pattern formed therein. In the centerportion of the Fresnel lens 13 f, a center region 13 g without theFresnel pattern is formed. The center region 13 g, unlike aconcentration region 13 h (portion with diagonal lines) therearound,does not contribute to concentration of light but allows light to passtherethrough. The diameter of the center region 13 g is about 2 mm, forexample.

FIG. 9 is a graph showing one example of the details of the Fresnelpattern. The horizontal axis represents the radius [mm] from the center,and the vertical axis represents the projection amount [mm] from thebase material 13 f 2. As shown in FIG. 9, the further out in the radialdirection, the greater the projection amount is (the difference betweenthe top of the projection and the bottom of the recess increases). Dueto such a pattern shape, light concentrating property similar to that ofa convex lens can be obtained. The center region 13 g at the centerportion does not contribute to concentration of light but allows lightto pass therethrough.

By affixing the Fresnel pattern formed in the silicone resin film 13 f 3to the base material 13 f 2, due to factors such as contraction of theadhesive and temperature change, the center region 13 g, originallyflat, is pulled outwardly to have a shape that is thinnest at the centerand thicker toward outside in a concave lens shape. Since this centerregion 13 g does not have the Fresnel pattern, the power generatingelement part 21 can be seen through the center region 13 g by the camera60 to 63.

That is, when the power generating element part 21 is to be viewed by acamera or the eye through the other portion (i.e., the concentrationregion 13 h) of the Fresnel lens 13 f than the center region 13 g, theview becomes blurry or the image is distorted, and thus, the powergenerating element part 21 may not be clearly seen. However, through thecenter region 13 g serving as a concave lens, the power generatingelement part 21 can be clearly seen.

Thus, by viewing the power generating element part 21 through the smallcenter region 13 g at the center portion of the Fresnel lens 13 f, it ispossible to perform alignment between the power generating element part21 and its corresponding Fresnel lens 13 f

It is inefficient to perform alignment between all the power generatingelement parts 21 and their corresponding Fresnel lenses 13 f Thus, forexample, alignment is performed on the power generating element parts 21at four corners and their corresponding Fresnel lenses 13 f at the fourcorners. Accordingly, highly accurate and quick alignment can beperformed.

Basically, however, by positioning the lens panel 13 such that, withrespect to each of at least two (two at positions distanced from eachother as much as possible) Fresnel lenses 13 f, the power generatingelement part 21 comes to the center of the field of view, it is possibleto easily realize the alignment between Fresnel lenses versus powergenerating element parts in the entirety of the lens panel 13. This isbecause both the power generating element parts 21 and the Fresnellenses 13 f are provided in the form of an array, and if alignment isperformed in a portion thereof, the effect of the alignment is alsoapplied to the entirety thereof.

FIG. 10 shows one example the manner of performing the alignment betweena Fresnel lens versus a power generating element part.

As described above, the light receiving surface 23 a is covered by theball lens 24, and thus, in the center region 13 g, the ball lens 24 canbe confirmed.

In addition, as described above, in the center portion of the ball lens24, the grid electrodes 31 can be recognized relatively clearly.

In the present embodiment, the ball lens 24 is fixed after the positionof its center has been adjusted so as to be aligned with the opticalaxis S of the Fresnel lens 13 f, the optical axis S being aligned withthe center of the light receiving surface 23 a.

Therefore, when the center region 13 g is viewed by the camera 60 to 63,the ball lens 24 can be seen, and at the same time, in the centerportion of the ball lens 24, the linear electrode portion 33 crossingthe first center grid electrode 31 a, and the cross portion 34 can beseen.

The control device 65 performs fine adjustment of the position of thelens panel 13, from the position of FIG. 10A where a part of the balllens 24 of the power generating element part 21 is seen at a not-alignedposition, to a position where the ball lens 24 can be seen at thecenter. Then, after a state is realized where the linear electrodeportion 33 and the cross portion 34 appear in the center region 13 g asshown in FIG. 10B, and then a state is realized where the cross portion34 has come to substantially the center of the center region 13 g asshown in FIG. 10C, alignment for this power generating element part 21is completed. In this manner, when the cross portions 34 recognized atthe power generating element parts 21 at the four corners can be seenthrough the center regions 13 g in the center portions of the respectiveFresnel lenses 13 f by the four cameras 60 to 63 at the respectivecenters, alignment is completed.

Each of the cameras 60 to 63 outputs the states recognized as above, ascaptured image data. Based on the captured image data indicating thestates as above and provided from each of the cameras 60 to 63, thecontrol device 65 obtains position information indicating the positionalrelation between the Fresnel lens 13 f and the cross portion 34.

Based on the obtained position information, the control device 65further obtains a movement amount for moving the lens panel 13 to anappropriate position, and controls the position adjuster 66 based onthis movement amount.

It should be noted that performing alignment at the four corners of thelens panel 13 is merely one example, and variations thereof can beconceivable. Basically, as described above, alignment can be performedat two positions (for example, both ends on a diagonal line) that aredistanced from each other as much as possible. That is, by positioningthe lens panel 13 such that, with respect to each of at least twoFresnel lenses 13 f, the power generating element part 21 comes to thecenter of the field of view, it is possible to easily realize alignmentbetween Fresnel lenses 13 f versus power generating element parts 21 inthe entirety of the lens panel 13.

The center region 13 g may be provided to all of the Fresnel lenses 13f, or may be provided to only some of the Fresnel lenses 13 f that areto be used in the alignment.

In the present embodiment, a case has been described in which each powergenerating element part 21 includes the ball lens 24. However, even in acase where the power generating element part 21 does not include theball lens 24 and the light receiving surface 23 a is exposed, each ofthe cameras 60 to 63 can confirm the cross portion 34 formed on thelight receiving surface 23 a of its corresponding power generatingelement part 21. Thus, positional adjustment of the lens panel 13 by theabove-described method can be performed.

The control device 65 may be configured by a computer including a CPU, astorage device, and the like. In this case, the functions as the controldevice 65 are realized by a computer program. In the storage device, thecomputer program for realizing the functions as the control device 65 isalso stored.

This computer program is a computer program for causing a computer toexecute a process regarding production of a concentrator photovoltaicmodule including:

a plurality of solar cells provided in a form of an array; and

a concentrating member in which a plurality of condenser lenses eachconcentrating sunlight incident on an incident surface thereof areformed at positions corresponding to the solar cells on optical axesthereof, wherein

on a light receiving surface of each solar cell, a plurality of gridelectrodes each formed in a linear shape are arrayed, and

the plurality of grid electrodes include a cross grid electrode forminga cross portion exhibiting a center-specific geometry caused byelectrodes crossing each other at the center of the light receivingsurface,

the computer program for causing the computer to execute:

-   -   a position information obtaining step of obtaining position        information indicating positional relation between a condenser        lens and a cross portion corresponding thereto at a time when        the condenser lens and a solar cell corresponding thereto are        seen from the incident surface side of the condenser lens; and    -   an adjustment step of performing positional adjustment between        the concentrating member and each solar cell based on the        position information.

3. EFFECTS

According to the solar cell 23 of the present embodiment, a plurality ofgrid electrodes 31 each formed in a linear shape are arrayed on thelight receiving surface 23 a. In addition, the plurality of gridelectrodes 31 include the first center grid electrode 31 a as a crossgrid electrode forming the cross portion 34 exhibiting a center-specificgeometry caused by electrodes crossing each other at the center of thelight receiving surface 23 a. Thus, in a case where condenser lensessuch as the Fresnel lens 13 f and the ball lens 24 which concentratesunlight toward the light receiving surface 23 a are to be disposed, theposition of the cross portion 34 can be recognized through the condenserlenses. Thus, based on the positional relation between the condenserlenses and the cross portion 34, it is possible to accurately adjust theposition of the optical axis of each of the condenser lenses to thecenter of the light receiving surface 23 a. As a result, it is possibleto perform accurate mutual alignment between the condenser lenses andtheir corresponding solar cell 23.

In the present embodiment, the first center grid electrode 31 a isprovided with the linear electrode portion 33 crossing the first centergrid electrode 31 a at the center of the light receiving surface 23 a.Thus, the cross portion 34 can be formed by the first center gridelectrode 31 a and the linear electrode portion 33. Accordingly, it ispossible to provide the cross portion 34 without greatly increasing thearea of the grid electrodes.

In the module 1M (the units 20) of the present embodiment, the gridelectrodes 31 of each solar cell 23 include a cross grid electrodeforming the cross portion 34. Thus, as in the above, it is possible toperform accurate mutual alignment between the lens panel 13 (Fresnellenses 13 f) and its corresponding solar cells 23.

The module 1M (the units 20) of the present embodiment further includesthe ball lenses 24 as the secondary condenser lenses, each ball lens 24disposed between a Fresnel lens 13 f and a solar cell 23 and configuredto guide sunlight concentrated by the Fresnel lens 13 f to the solarcell 23. Also in this case, based on the positional relation between theball lens 24 and the cross portion 34 and the positional relationbetween the Fresnel lens 13 f and the cross portion 34, it is possibleto accurately adjust the position of the optical axis of each condenserlens to the center of its corresponding light receiving surface 23 a. Asa result, even when the ball lens 24 is provided, it is possible toperform accurate mutual alignment between each condenser lens and itscorresponding solar cell 23.

In the present embodiment, each ball lens 24 is fixed to the solar cell23 side so as to cover the light receiving surface 23 a of the solarcell 23. Also in this case, the position of the cross portion 34 can berecognized through each condenser lens, and thus, it is possible toperform accurate mutual alignment between each condenser lens and itscorresponding solar cell 23.

Also in the method for producing the module 1M of the presentembodiment, the grid electrodes 31 of each solar cell 23 include a crossgrid electrode forming the cross portion 34. Therefore, the center ofthe light receiving surface 23 a can be easily recognized by means ofthe cross portion 34, and it is possible to perform accurate mutualalignment between the lens panel 13 and its corresponding solar cells23.

4. MODIFICATIONS

FIG. 11 shows the light receiving surface 23 a of the solar cell 23according to a modification, and shows another aspect of the linearelectrode portion 33.

In FIG. 11, the linear electrode portion 33 is in an open state whereboth ends thereof are not connected to other grid electrodes 31.

Also in the above case, the linear electrode portion 33 and the firstcenter grid electrode 31 a forms the cross portion 34 by crossing eachother at the center of the light receiving surface 23 a. Thus, it ispossible to perform accurate mutual alignment between the condenser lensguiding sunlight to the light receiving surface 23 a and itscorresponding solar cell 23.

It should be noted that the length of the linear electrode portion 33 inthe longitudinal direction thereof can be changed as appropriate as longas the linear electrode portion 33 crosses the first center gridelectrode 31 a at the center of the light receiving surface 23 a.

In FIG. 4 and FIG. 11, cases have been described in which the linearelectrode portion 33 is formed in parallel to the bus electrodes 32.However, it is sufficient that the linear electrode portion 33 crossesthe first center grid electrode 31 a. The linear electrode portion 33may be provided so as to cross the first center grid electrode 31 a atan angle other than 90 degrees, for example, at an angle of 45 degrees.

5. OTHERS

FIG. 12A shows the solar cell 23 according to another embodiment, andshows the light receiving surface 23 a of the solar cell 23. FIG. 12Bshows one example of a captured image of the light receiving surfaceshown in FIG. 12A obtained by a camera part through the ball lens 24.

The present embodiment is different from the above embodiment in that apair of second center grid electrodes 31 b passing the center of thelight receiving surface 23 a are provided.

In FIG. 12A, the pair of second center grid electrodes 31 b are arrayedin the center portion in the width direction of the light receivingsurface 23 a, and the second center grid electrodes 31 b each pass thecenter of the light receiving surface 23 a, thereby forming a cross gridelectrode.

The pair of second center grid electrodes 31 b include: obliqueelectrode portions 36 forming the cross portion 34 by extending indirections that cross other grid electrodes 31 and by crossing eachother; and parallel electrode portions 37 each extending in parallel tothe other grid electrodes 31, from both ends of a corresponding one ofthe oblique electrode portions 36 toward edge sides of the lightreceiving surface 23 a where the bus electrodes 32 are respectivelyprovided.

As shown in FIG. 12B, also in this case, image portions 52 b of the pairof second center grid electrodes 31 b passing the center of the lightreceiving surface 23 a appear in the center portion of the image portion51 of the ball lens 24. In FIG. 12B, the portions with hatching indicatethe image portions 52 of the grid electrodes 31 (the image portions 52 bof the second center grid electrodes 31 b).

Further, in the center portion of the image portion 51 of the ball lens24, there appear image portions 56 of the oblique electrode portions 36,and image portions 57 of the parallel electrode portions 37 forming thepair of second center grid electrodes 31 b, and further, the imageportion 54 of the cross portion 34.

Thus, also in the present embodiment, as in the above embodiment, it ispossible to accurately dispose the ball lens 24 on the optical axis S.

In the light receiving surface 23 a of the solar cell 23 shown in FIG.4, there exists the first center grid electrode 31 a extending inparallel to the other grid electrodes 31 and passing the center of thelight receiving surface 23 a. By use of this first center grid electrode31 a, the cross portion 34 is formed without increasing the area of thegrid electrodes as much as possible.

On the other hand, as shown in FIG. 12A, in a case where the firstcenter grid electrode 31 a extending in parallel to the other gridelectrodes 31 and passing the center of the light receiving surface 23 adoes not exist, if the pair of second center grid electrodes 31 bincluding the oblique electrode portions 36 and the parallel electrodeportions 37 are arrayed in the center portion in the width direction ofthe light receiving surface 23 a as in the present embodiment, it ispossible to provide the cross portion 34.

As described above, in the present embodiment, even when the firstcenter grid electrode 31 a extending in parallel to the other gridelectrodes 31 and passing the center of the light receiving surface 23 adoes not exist, the cross portion 34 can be formed by the pair of secondcenter grid electrodes 31 b including the oblique electrode portions 36.Accordingly, it is possible to provide the cross portion 34 withoutgreatly increasing the area of the grid electrodes.

6. CONCLUSION

The embodiments disclosed herein are to be considered in all respects asillustrative and not restrictive. The scope of the present invention isindicated by the appended claims rather than by the foregoing meaning,and all changes that come within the meaning and range of equivalency ofthe claims are therefore intended to be embraced therein.

REFERENCE SIGNS LIST

-   -   1 concentrator photovoltaic panel    -   1M concentrator photovoltaic module    -   2 post    -   3 base    -   11 housing    -   11 a bottom surface    -   11 c opening    -   12 flexible printed circuit    -   13 lens panel    -   13 f Fresnel lens    -   13 f 1 incident surface    -   13 f 2 base material    -   13 f 3 silicone resin film    -   13 g center region    -   13 h concentration region    -   14 connector    -   15 wall part    -   15 a end surface    -   16 flexible substrate    -   20 unit    -   21 power generating element part    -   22 resin frame    -   23 solar cell    -   23 a light receiving surface    -   24 ball lens    -   24 a incident surface    -   25 resin    -   30 semiconductor substrate    -   31 grid electrode    -   31 a first center grid electrode    -   31 b second center grid electrode    -   32 bus electrode    -   33 linear electrode portion    -   34 cross portion    -   36 oblique electrode portion    -   37 parallel electrode portion    -   40 ball lens mounting device    -   41 positional adjustment section    -   42 controller    -   43 camera part    -   44 holder    -   44 a holding hole    -   45 drive unit    -   50 captured image    -   51 image portion of ball lens    -   52 image portion of grid electrode    -   52 a image portion of first center grid electrode    -   52 b image portion of second center grid electrode    -   53 image portion of linear electrode portion    -   54 image portion of cross portion    -   56 image portion of oblique electrode portion    -   57 image portion of parallel electrode portion    -   60 to 63 camera    -   65 control device    -   66 position adjuster    -   100 concentrator photovoltaic apparatus

The invention claimed is:
 1. A solar cell in which a plurality of gridelectrodes each formed in a linear shape are arrayed on a lightreceiving surface of the solar cell, wherein the plurality of gridelectrodes include: a pair of first grid electrodes formed straightacross the light receiving surface, the pair of first grid electrodesbeing arranged in parallel and arranged on both sides of a center of thelight receiving surface, and a pair of cross grid electrodes forming across portion exhibiting a center-specific geometry caused by the pairof cross grid electrodes crossing each other at a center of the lightreceiving surface, the pair of cross grid electrodes formed entirely inan area between the pair of first grid electrodes, and second gridelectrodes, extending in parallel to the pair of first grid electrodesand arrayed outside the area, the second grid electrodes being all gridelectrodes of the plurality of grid electrodes excluding the pair offirst grid electrodes and the pair of cross electrodes.
 2. The solarcell according to claim 1, wherein the pair of cross grid electrodesincludes: a center grid electrode extending in parallel to the pair offirst grid electrodes and passing the center of the light receivingsurface, and a linear electrode crossing the center grid electrode atthe center of the light receiving surface, the linear electrode beingshorter than the center grid electrode.
 3. The solar cell according toclaim 2, wherein the linear electrode has both ends thereof respectivelyconnected to the pair of first grid electrodes.
 4. The solar cellaccording to claim 1, wherein the pair of cross grid electrodes include:oblique electrode portions extending in directions that cross the pairof first grid electrodes; and parallel electrode portions each extendingin parallel to the pair of first grid electrodes, from both ends of acorresponding one of the oblique electrode portions toward edge sides ofthe light receiving surface, and the oblique electrode portions crosseach other to form the cross portion.
 5. A concentrator photovoltaicunit comprising: a solar cell in which a plurality of grid electrodeseach formed in a linear shape are arrayed on a light receiving surfaceof the solar cell; and a condenser lens configured to concentratesunlight on the solar cell, wherein the plurality of grid electrodesinclude: a pair of first grid electrodes formed straight across thelight receiving surface, the pair of first grid electrodes beingarranged in parallel and arranged on both sides of a center of the lightreceiving surface, and a pair of cross grid electrodes forming a crossportion exhibiting a center-specific geometry caused by the pair ofcross grid electrodes crossing each other at a center of the lightreceiving surface, the pair of cross grid electrodes formed entirely inan area between the pair of first grid electrodes, and second gridelectrodes, extending in parallel to the pair of first grid electrodesand arrayed outside the area, the second grid electrodes being all gridelectrodes of the plurality of grid electrodes excluding the pair offirst grid electrodes and the pair of cross electrodes.
 6. Theconcentrator photovoltaic unit according to claim 5, further comprisinga secondary condenser lens disposed between the condenser lens and thesolar cell and configured to guide sunlight concentrated by thecondenser lens to the solar cell.
 7. The concentrator photovoltaic unitaccording to claim 6, wherein the secondary condenser lens is a balllens and is fixed to the solar cell side so as to cover the lightreceiving surface of the solar cell.
 8. A concentrator photovoltaicmodule comprising: a plurality of solar cells provided in a form of anarray; and a concentrating member in which a plurality of condenserlenses each concentrating sunlight incident on an incident surfacethereof are formed at positions corresponding to the solar cells onoptical axes thereof, wherein on a light receiving surface of each solarcell, a plurality of grid electrodes each formed in a linear shape arearrayed, and the plurality of grid electrodes include: a pair of firstgrid electrodes formed straight across the light receiving surface, thepair of first grid electrodes being arranged in parallel and arranged onboth sides of a center of the light receiving surface, and a pair ofcross grid electrodes forming a cross portion exhibiting acenter-specific geometry caused by the pair of cross grid electrodescrossing each other at a center of the light receiving surface, the pairof cross grid electrodes formed entirely in an area between the pair offirst grid electrodes, and second grid electrodes, extending in parallelto the pair of first grid electrodes and arrayed outside the area, thesecond grid electrodes being all grid electrodes of the plurality ofgrid electrodes excluding the pair of first grid electrodes and the pairof cross electrodes.